1. Technical Field
The present disclosure relates to an imaging device.
2. Description of the Related Art
Charge-coupled device (CCD) image sensors and complementary metal-oxide-semiconductor (CMOS) image sensors are being used widely in devices such as digital cameras. As is well known, these image sensors include photodiodes formed on a semiconductor substrate. Otherwise, a structure is known in which photoelectric converters including a photoelectric conversion layer are arranged above a semiconductor substrate. For example, Japanese Unexamined Patent Application Publication No. 2011-228621 discloses a solid-state image sensor element in which photoelectric converter elements P including a photoelectric conversion layer are arranged on top of an insulating layer 20 covering a semiconductor substrate 10 on which a signal readout circuit 11 is formed (see FIG. 2). With a so-called laminated structure like the above, the photoelectric converters are arranged above the signal readout circuit, and thus the aperture ratio is easily maintained. Consequently, such a structure has the advantage of enabling higher pixel densities.
In the field of imaging devices, there is demand for noise reduction. In particular, there is demand to reduce the kTC noise produced when resetting the electric charge generated by photoelectric conversion (also called “reset noise”). U.S. Pat. No. 6,532,040 proposes the cancellation of reset noise by providing a feedback amplifier on each pixel column in the imaging area, and forming a feedback path that includes the feedback amplifiers. The entire contents of U.S. Pat. No. 6,532,040 are incorporated by reference herein.